The invention relates to a plastic container of rectangular cross-sectional shape which has a sealable cover. The cover has a projecting inner flange which protrudes into the opening of the container and an outer flange which overlaps the upper edge of the container. Between the inner and outer flange a gasket is arranged which is pressed against the edge of the container. The cover is maintained in closed position by means of fastening means at the outside of the container and the outer rim of the cover.
In order to obtain a safe sealing of the comparatively elastic covers in case of rough handling, it has been necessary heretofore to provide for a multiplicity of fastening members distributed along the circumference of the cover. These fastening members had to be closed one by one and by hand by bringing them into contact with the lock devices provided on the wall of the container. To assure a high quality of seal the fastening members had to be secured moreover by a sealing wire.
In spite of this rather cumbersome lock procedure, sudden impact stresses resulted in a bending up of the edge of the cover between different fastening members and thus would cause a lifting of the seal. The reason was the distance between the individual fastening members which was particularly undesirable in case of the straight areas of the cover edge. The use of a special strap under tension to avoid this shortcoming proved rather expensive.
It is therefore an object of the present invention to obtain an adequate seal of the cover and at the same time to permit the sealing and closure operation to be carried out without loss of much time and with comparatively simple mechanical means.